octa-

a combining form occurring in loanwords from Greek and Latin, where it meant “eight” (octagon; octastyle), on this model, used in the formation of compound words, and in chemical terms specialized to mean “having eight atoms” (octavalent).

Also oct-, octo-.

Origin of octa-

< Greek okta-, combining form of oktṓ eight

Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

British Dictionary definitions for octa-

octa-

combining form

a variant of octo-

Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Word Origin and History for octa-

before vowels oct-, word-forming element meaning "eight," from Greek okta-, okt-, from PIE *okto(u) "eight" (see eight). The variant form octo- often appears in words taken from Latin, but the Greek form is said to be the more common in English.